Today, many wireless communication techniques are being proposed to achieve high-speed mobile communication. Among them, an Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) scheme is accepted as one of the most promising techniques for a next generation wireless communication. The OFDM scheme is expected to be widely used in future wireless communication techniques, and is currently used as a standard in the Institute of Electrical and Electronics Engineers (IEEE) 802.16-based Wireless Metropolitan Area Network (WMAN) known as the 3.5 generation technology.
The OFDM/OFDMA-based broadband wireless communication system can create a plurality of Service Flows (SFs) for each user (or mobile station (MS)). The created plurality of SFs can support different Quality of Services (QoSs) or service classes.
In communication systems, accounting information is used as a reference for imposing a service charge to a user. Thus, accuracy is required in the accounting information, and an accounting process needs to be performed in more detailed steps to provide a differentiated service to the user.
A conventional accounting method is based on a single service in which accounting information is generated under the assumption that one service is activated for an MS. Therefore, the convention accounting method cannot be used when the MS activates a plurality of services. A method of generating an accounting session for each SF has recently been proposed, but this method has a drawback in that accounting is not accurate since an SF state and a Media Access Control (MAC) state of the MS are not taken into account.
In a broadband wireless communication system, the MAC state of the MS is classified into an awake state, a sleep state, and an idle state, and the SF state is classified into a provisioned state, an admitted state, and an active state.
The awake state denotes a state in which there is a traffic flow per the MS. If there is no traffic flow during a sleep timer period in the awake state, the MS transitions from the awake state to the sleep state. If there is no traffic flow during an idle timer period, the MS transitions to the idle state. When in the idle state, a radio link connection is released but SF information is maintained in an Access Service Network-Gateway (ASN_GW).
The active state denotes a state in which there is a traffic flow per the SF. The admitted state denotes a state in which a Traffic Connection IDentifier or a Transport Connection IDentifier (TCID) is allocated and a resource is reserved. The provisioned state denotes a state in which only a Service Flow IDentification (SFID) is allocated. Herein, if there is no traffic flow during a preset time period in the active state, the SF may transition from the active state to the admitted state, and if there is no traffic flow during a longer time period, the SF may transition to the provisioned state. Further, when a state transition occurs, the MS and an Access Service Network (ASN) can transition to another state after exchanging a message according to the state transition.
In the conventional accounting processing method, an SF is generated when a transition occurs from the idle state to the awake state, and the SF is terminated when a transition occurs from the awake state to the idle state. That is, the sleep state and the awake state are equally treated, and likewise, the admitted state and the active state are equally treated. However, accounting may not be imposed in the admitted state since resources are not actually used, or may be imposed since SF generation is limited in another aspect. In addition, since the sleep state uses less resources than the active state, accounting may be differently applied according to a policy of a service provider. To apply various accounting policies, an accounting policy has to be individually applied to each MAC state and each SF state. In addition, in the conventional method, an accounting session has to be released and generated whenever a state transition occurs, which leads to a problem in that a signaling overhead increases. Accordingly, there is a need for a flexible and optimized accounting processing method in which an accounting policy can be individually applied to each MAC state and each SF state and in which a signaling overhead can be reduced.